There is disclosed herein a process for recovering methylene chloride from an aqueous water solution and the recovered methylene chlorine produced thereby. More particularly, the exemplary embodiment disclosed herein relates to the use of a recycle stream in a batch distillation process for recovering methylene chloride from a waste stream. The process reduces hazardous waste and improves the reclaim efficiency of methylene chloride. The exemplary embodiment finds particular application in conjunction with recovering methylene chloride used as a solvent in photoreceptor fabrication, and will be described with particular reference thereto. However, it is to be appreciated that the present exemplary embodiment is also amenable to other like applications.
Photoreceptor fabrication requires reagent grade (i.e., 99.99% purity) methylene chloride which is used as a solvent. Typically, a recycling system captures the solvent as it vaporizes in a carbon bed. The captured solvent is removed from the carbon bed with steam and the resulting water/methylene chloride mixture is distilled to recover the solvent. Previous operations monitored the distillation process and diverted the recovered solvent once the quality or concentration level of the solvent fell below reagent grade. This technical grade material can be sold to entities who market it as paint remover, etc. However, this practice requires that the methylene chloride solvent is frequently replenished during the photoreceptor fabrication process. Furthermore, another disadvantage of this practice is that the low quality solvent shipped to other entities be designated as hazardous waste.
The present exemplary embodiment contemplates a new and improved process for recovering methylene chloride which overcomes the above-referenced problems and others.